“Here is Willis’s fundamental argument: The more we learn about Earth—our one ‘pale blue data point’ for a planet on which life has definitively arisen—the more qualified we will be to recognize signs of life elsewhere. . . . [A] joyful account.”—Steven Poole, The Wall Street Journal A thrilling tour of Earth that shows the search for extraterrestrial life starts in our own backyard.  Is there life off Earth? Bound by the limitations of spaceflight, a growing number of astrobiologists investigate the question by studying life on our planet. Astronomer and author Jon Willis shows us how it’s done, allowing readers to envision extraterrestrial landscapes by exploring their closest Earth analogs. With Willis, we dive into the Pacific Ocean from the submersible-equipped E/V Nautilus to ponder the uncharted seas of Saturn’s and Jupiter’s moons; search the Australian desert for some of Earth’s oldest fossils and consider the prospects for a Martian fossil hunt; visit mountaintop observatories in Chile to search for the telltale twinkle of extrasolar planets; and eavesdrop on dolphins in the Bahamas to imagine alien minds.  With investigations ranging from meteorite hunting to exoplanet detection, Willis conjures up alien worlds and unthought-of biological possibilities, speculating what life might look like on other planets by extrapolating from what we can see on Earth, our single “pale blue dot”—as Carl Sagan famously called it—or, in Willis’s reframing, scientists’ “pale blue data point.”